Radio frequency signal combiner and method of operating same

Abstract

To provide a switchable bidirectional radio frequency coupler.SOLUTION: A bidirectional coupler 300 includes input ports CPL_IN, CPL_ANT, output ports CPL_FL, CPL_FH, CPL_R, a main transmission line 302 coupled between the input ports and the output ports, and a coupled transmission line to be electromagnetically coupled to the main transmission line. The coupled transmission line includes a first segment 304a, a second segment 304b, and a switch 306 for coupling the first segment and the second segment during a first operation mode, and decoupling the first transmission line and the second transmission line during a second operation mode. This radio frequency coupling can be used in a front end modules of a communication device such as a mobile phone.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 152,409, filed on Feb. 23, 2021, entitled "Smart Bidirectional Coupler with Switchable Inductor", which is hereby incorporated by reference in its entirety for all purposes.

[0002] The present disclosure generally relates to bidirectional couplers. More particularly, aspects of the present disclosure relate to systems and methods for improving coupler performance using a switchable inductor.

Summary of the Invention

[0003] According to an aspect of the present disclosure, a radio frequency signal coupler is provided. The radio frequency signal coupler includes an input port, an output port, a main transmission line coupled between the input port and the output port, and a coupled transmission line electromagnetically coupled to the main transmission line. The coupled transmission line includes a first transmission line, a second transmission line, and a switch configured to couple the first transmission line and the second transmission line during a first operating mode and to decouple the first transmission line and the second transmission line during a second operating mode.

[0004] According to one embodiment, the switch is configured to couple the first transmission line and the second transmission line during the first operating mode to provide a first coupling coefficient and to decouple the first transmission line and the second transmission line during the second operating mode to provide a second coupling coefficient.

[0005] According to other embodiments, the first operating mode corresponds to a first frequency range, the second operating mode corresponds to a second frequency range, and the second frequency range is different from the first frequency range.

[0006] According to an example, the first coupling coefficient over the first frequency range is substantially the same as the second coupling coefficient over the second frequency range.

[0007] In other examples, a radio frequency coupler operates in a first and second operating mode to maintain substantially constant insertion loss between the input port and the output port over a first and second frequency range.

[0008] In a further example, a radio frequency signal coupler is configured as a bidirectional coupler, with an input port and an output port each configured to receive an input radio frequency signal and provide an output radio frequency signal.

[0009] According to a further embodiment, the radio frequency signal coupler further includes at least one forward output port and a reverse output port, and the coupled transmission line is coupled between the at least one forward output port and the reverse output port.

[0010] For example, at least one forward output port is configured to provide a forward coupling signal when an input radio frequency signal is received at the input port.

[0011] In other examples, a radio frequency signal coupler operates in a first and second operating mode to maintain a substantially constant power level of the forward-coupled signal across a first and second frequency range.

[0012] In a further example, a reverse output port is configured to provide a reverse coupling signal when an input radio frequency signal is received at the output port.

[0013] In other examples, a radio frequency signal coupler operates in a first and second operating mode to maintain a substantially constant power level of the reverse-coupled signal across a first and second frequency range.

[0014] In other examples, at least one forward output port and one reverse output port are selectively coupled to a common output port.

[0015] In some examples, at least one forward output port and one reverse port are selectively coupled to an adjustable termination circuit. In these examples, the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

[0016] According to another embodiment, the coupled transmission line includes a third transmission line, and the switch is configured to couple the third transmission line to the first and / or second transmission line during a third operating mode corresponding to a third frequency range, which is different from the first and second frequency ranges. According to a further embodiment, the switch is configured to couple the third transmission line to the first and / or second transmission line during a third operating mode to give a third coupling coefficient.

[0017] Other aspects of this disclosure provide a method for operating a radio frequency signal coupler. The method includes receiving a radio frequency signal at one of an input port and an output port; supplying the radio frequency signal to a main transmission line coupled between the input port and the output port; and electromagnetically coupling a portion of the radio frequency signal to the coupling transmission line, the coupling transmission line including a first transmission line and a second transmission line; and operating a switch to couple the first transmission line and the second transmission line during a first operating mode and to discouple the first transmission line and the second transmission line during a second operating mode.

[0018] According to one embodiment, operating the switch to couple a first transmission line and a second transmission line during the first operating mode further includes providing a first coupling coefficient during the first operating mode.

[0019] For example, the first coupling coefficient corresponds to the first frequency range.

[0020] According to one embodiment, operating a switch to uncouple the first transmission line and the second transmission line during the second operating mode further includes providing a second coupling coefficient during the second operating mode.

[0021] For example, the second coupling coefficient corresponds to the second frequency range, which is different from the first frequency range.

[0022] For example, the first coupling coefficient over the first frequency range is substantially the same as the second coupling coefficient over the second frequency range.

[0023] According to a further embodiment, the method further includes operating the radio frequency signal coupler in a first and second operating mode to maintain substantially constant insertion loss between the input port and the output port over a first and second frequency range.

[0024] According to aspects of this disclosure, a radio frequency signal coupler is provided. The radio frequency signal coupler includes an input port, an output port, a main inductor coupled between the input port and the output port, and a coupling inductor electromagnetically coupled to the main inductor. The coupling inductor includes a first inductor, a second inductor, and a switch configured to couple the first inductor and the second inductor during a first operating mode and to discouple the first inductor and the second inductor during a second operating mode.

[0025] According to one embodiment, the switch is configured to couple a first inductor and a second inductor during a first operating mode to give a first coupling coefficient, and to uncouple the first inductor and the second inductor during a second operating mode to give a second coupling coefficient.

[0026] In another embodiment, the first operating mode corresponds to a first frequency range, and the second operating mode corresponds to a second frequency range, and the second frequency range and the first frequency range are different.

[0027] For example, the first coupling coefficient over the first frequency range is substantially the same as the second coupling coefficient over the second frequency range.

[0028] According to another example, the radio frequency coupler operates in a first operating mode and a second operating mode so as to maintain a substantially constant insertion loss between the input port and the output port over a first frequency range and a second frequency range.

[0029] According to a further example, the radio frequency signal coupler is configured as a bidirectional coupler, and the input port and the output port are each configured to receive an input radio frequency signal and provide an output radio frequency signal.

[0030] According to a further embodiment, the radio frequency signal coupler further includes at least one forward output port and a reverse output port, and the coupling inductor is coupled between the at least one forward output port and the reverse output port.

[0031] According to one example, at least one forward output port is configured to provide a forward coupling signal when an input radio frequency signal is received at the input port.

[0032] According to another example, the radio frequency signal coupler operates in a first operating mode and a second operating mode so as to maintain the power level of the forward coupling signal substantially constant over a first frequency range and a second frequency range.

[0033] According to a further example, the reverse output port is configured to provide a reverse coupling signal when an input radio frequency signal is received at the output port.

[0034] According to another example, the radio frequency signal coupler operates in a first operating mode and a second operating mode so as to maintain the power level of the reverse coupling signal substantially constant over a first frequency range and a second frequency range.

[0035] According to another example, at least one forward output port and the reverse port are selectively coupled to a common output port.

[0036] In some examples, at least one forward output port and one reverse port are selectively coupled to an adjustable termination circuit. In these examples, the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

[0037] According to another embodiment, the coupled inductor includes a third inductor, and the switch is configured to couple the third inductor to the first and / or second inductor during a third operating mode corresponding to a third frequency range, which is different from the first and second frequency ranges. According to a further embodiment, the switch is configured to couple the third inductor to the first and / or second inductor during a third operating mode to give a third coupling coefficient.

[0038] Other aspects of this disclosure provide a method for operating a radio frequency signal coupler. The method includes receiving a radio frequency signal at one of an input port and an output port; supplying the radio frequency signal to a main inductor coupled between the input port and the output port; and electromagnetically coupling a portion of the radio frequency signal to a coupling inductor, the coupling inductor comprising a first inductor and a second inductor; and operating a switch to couple the first inductor and the second inductor during a first operating mode and to discouple the first inductor and the second inductor during a second operating mode.

[0039] According to one embodiment, operating the switch to couple the first inductor and the second inductor during the first operating mode further includes providing a first coupling coefficient during the first operating mode.

[0040] For example, the first coupling coefficient corresponds to the first frequency range.

[0041] According to one embodiment, operating a switch to uncouple the first inductor and the second inductor during the second operating mode further includes providing a second coupling coefficient during the second operating mode.

[0042] For example, the second coupling coefficient corresponds to the second frequency range, which is different from the first frequency range.

[0043] For example, the first coupling coefficient over the first frequency range is substantially the same as the second coupling coefficient over the second frequency range.

[0044] According to a further embodiment, the method further includes operating the radio frequency signal coupler in a first and second operating mode to maintain substantially constant insertion loss between the input port and the output port over a first and second frequency range.

[0045] Further aspects of the present disclosure provide a radio frequency signal coupler including an input port, an output port, a primary inductance coupled between the input port and the output port, and a coupling inductance electromagnetically coupled to the primary inductance. The coupling inductance includes a first inductance, a second inductance, and a switch configured to couple the first inductance and the second inductance during a first operating mode and to uncouple the first inductance and the second inductance during a second operating mode.

[0046] In some examples, the first inductance and the second inductance may be a transmission line or an inductor. [Brief explanation of the drawing]

[0047] Various aspects of at least one embodiment are described below with reference to accompanying drawings, which are not intended to be drawn to scale. The drawings are included to illustrate and further illustrate the various aspects and embodiments and are incorporated herein and constitute part of this specification, but are not intended to define the limits of the invention. In the drawings, identical or substantially identical components shown in different drawings are represented by the same number. For clarity, not all components are marked in all drawings.

[0048] [Figure 1] This is a block diagram of the front-end module. [Figure 2] This is a schematic diagram of a radio frequency coupler. [Figure 3] This is a schematic diagram of a radio frequency coupler relating to the various aspects described here. [Figure 4A] This is a schematic diagram of a radio frequency coupler operating in a first operating mode relating to the multiple aspects described herein. [Figure 4B] This is a schematic diagram of a radio frequency coupler operating in a second operating mode relating to the multiple aspects described herein. [Figure 5] This is a set of graphs showing the performance of the radio frequency coupler in relation to the various aspects described here. [Figure 6] This is a schematic diagram of the radio frequency coupler array relating to the various aspects described here. [Figure 7A] This is a schematic diagram of the radio frequency coupler array operating in the first state relating to the multiple aspects described herein. [Figure 7B] This is a schematic diagram of the radio frequency coupler array operating in the second state relating to the multiple aspects described herein. [Figure 7C] This is a schematic diagram of a radio frequency coupler array operating in the third state relating to the multiple aspects described herein. [Figure 7D] This is a schematic diagram of the radio frequency coupler array operating in the fourth state relating to the multiple aspects described herein. [Figure 8] This is the layout of the radio frequency coupler relating to the multiple aspects described here. [Modes for carrying out the invention]

[0049] Multiple aspects and examples are directed towards multiple bidirectional couplers and their components, as well as towards devices, modules, and systems that incorporate them.

[0050] It is clear that the embodiments of the methods and apparatus described herein are not limited in their application to the details of configuration and arrangement described below or shown in the accompanying drawings. These methods and apparatus may be implemented in other embodiments and may be carried out or performed in various ways. Specific implementation examples are given herein for illustrative purposes only and are not intended to be limiting. Furthermore, the expressions and terms used herein are for illustrative purposes only and should not be considered limiting. The use herein of “includes,” “equips,” “has,” “contains,” and their variations means that they encompass the items and equivalents listed later, as well as additional items. References to “or” and “or else” are interpreted inclusively, and any item described using “or” and “or else” may refer to one, more than one, or all of the items described.

[0051] Figure 1 is a block diagram showing an example of a typical arrangement of a radio frequency (RF) "front-end" subsystem or module (FEM) 100 that may be used in a communication device such as a mobile phone to transmit and receive RF signals. The FEM 100 shown in Figure 1 includes a transmit path (TX) configured to supply a signal to an antenna for transmission, and a receive path (RX) to receive a signal from the antenna. In the transmit path (TX), a power amplifier module 110 provides gain to an RF signal 105 input to the FEM 100 via an input port 101, thereby generating an amplified RF signal. The power amplifier module 110 may include one or more power amplifiers (PAs).

[0052] The FEM100 further includes a filtering subsystem or module 120 which may include one or more filters. A directional coupler 130 can be used to extract a portion of the power from the RF signal traveling between the power amplifier module 110 and the antenna 140 connected to the FEM100. The antenna 140 can transmit and receive RF signals. A switching circuit 150, also called an antenna switch module (ASM), can be used to switch the transmit mode and receive mode of the FEM100, for example, between different transmit frequency bands or receive frequency bands. In a given example, the switching circuit 150 may operate under the control of a controller 160. As shown in the figure, the directional coupler 130 may be placed between the filtering subsystem 120 and the switching circuit 150. In other examples, the directional coupler 130 may be placed between the power amplifier module 110 and the filtering subsystem 120, or between the switching circuit 150 and the antenna 140.

[0053] The FEM100 may also include a receiving path (RX) configured to process the signal received by the antenna 140 and provide the received signal to a signal processor (e.g., a transceiver) via the output port 171. The receiving path (RX) may include one or more low-noise amplifiers (LNAs) 170 to amplify the signal received from the antenna. Although not shown, the receiving path (RX) may also include one or more filters to filter the received signal.

[0054] As described above, directional couplers (e.g., directional coupler 130) can be used in front-end module (FEM) products such as radio transceivers and radio handsets. For example, directional couplers can also be used to detect and monitor RF output power. When an RF signal generated by an RF source is applied to a load such as an antenna, a portion of the RF signal may be reflected from the load back to the RF source. An RF coupler may be included in the signal path between the RF source and the load to provide indication of the forward RF power of the RF signal traveling from the RF source to the load, and / or the reverse RF power reflected from the load. RF couplers include, for example, directional couplers, bidirectional couplers, and multiband couplers (e.g., dualband couplers).

[0055] Referring to Figure 2, the RF coupler 200 typically has a power input port 202, a power output port 204, a coupling port 206, and an isolation port 208. The electromagnetic coupling mechanism, which may include inductive or capacitive coupling, is typically provided by two parallel or overlapping transmission lines, such as microstrips, strip lines, or coplanar lines. The transmission line 210 extending between the power input port 202 and the power output port 204 is referred to as the main line and can supply the majority of the signal from the power input port 202 to the power output port 204. The transmission line 212 extending between the coupling port 206 and the isolation port 208 is referred to as the coupling line and can be used to extract a portion of the power traveling between the power input port 202 and the power output port 204 for measurement. In some examples, the amount of inductance provided by transmission lines 210 and 212, respectively, corresponds to the length of each transmission line. In the given example, an inductor coil can be used instead of the transmission lines 210 and 212.

[0056] When the termination impedance 214 is presented to the isolation port 208 (shown in Figure 2), the forward RF power traveling from the power input port 202 to the power output port 204 is indicated to the coupling port 206. Similarly, when the termination impedance is presented to the coupling port 206, the reverse RF power traveling from the power output port 204 to the power input port 202 is indicated to the coupling port 206, which is now effectively the isolation port for the reverse RF power. The termination impedance 214 is typically implemented by a 50-ohm shunt resistor in various conventional RF couplers, but in other examples, the termination impedance 214 may provide different impedance values ​​for a particular operating frequency. In some examples, the termination impedance 214 may be adjustable to support a number of operating frequencies.

[0057] In one example, the RF coupler 200 is configured to provide coupling coefficients corresponding to the mutual coupling of transmission line 210 (or first inductor coil) to transmission line 212 (or second inductor coil) and the capacitive coupling of transmission line 210 (or first inductor coil) to transmission line 212 (or second inductor coil). In some examples, the coupling coefficients may be a function of the distance between transmission lines 210 and 212 and the inductances of the transmission lines 210 and 212. Often, the coupling coefficients increase as the frequency increases. As the coupling coefficients increase, more power is coupled from the main line (i.e., transmission line 210) to the coupling line (i.e., transmission line 212), increasing the insertion loss of the RF coupler 200.

[0058] Therefore, RF couplers are typically designed to achieve a desired coupling coefficient at a specific frequency (or band). However, in some cases, RF couplers are bidirectional and configured for use in multimode and multifrequency applications. For example, an RF coupler may be included in an FEM configuration (e.g., FEM100 in Figure 1) that operates in a first and second operating mode. In one example, the first operating mode corresponds to a low-frequency signal (e.g., 1 GHz) and the second operating mode corresponds to a high-frequency signal (e.g., 3 GHz). In some examples, if the RF coupler is designed to achieve a desired coupling coefficient during the first operating mode, the coupling coefficient may become stronger than intended or desired during the second operating mode. Therefore, an attenuator can be used to reduce the coupling power during the second operating mode. Similarly, if the insertion loss of the RF coupler increases during the second operating mode, the output power of the power amplifier module 110 (or other RF source) may increase during the second operating mode to compensate for the increased insertion loss.

[0059] In some cases, including an attenuator to reduce coupled power during the second operating mode (i.e., high-frequency mode) may increase the footprint of the RF coupler and the overall package size of the FEM. In addition, attenuating coupled power during the second operating mode may reduce the accuracy of output power monitoring provided by the RF coupler. For example, the attenuation provided by the attenuator may not be able to compensate for the exact amount of excess power corresponding to the increased coupling coefficient, and the exact value of the attenuation provided by the attenuator may vary. Similarly, a bypass switch may be required to bypass the attenuator during the first operating mode (i.e., low-frequency mode). The bypass switch not only occupies extra space but may also introduce additional losses to the coupled power signal path. In addition, operating the power amplifier module 110 (or other RF source) to provide high output power during the second operating mode may result in a decrease in the efficiency of the power amplifier module 110 and an increase in the power consumption of the FEM 100.

[0060] Alternatively, to support a first and second operating mode, the FEM100 can be configured to include separate RF couplers for each mode. For example, the FEM100 may include a first RF coupler designed to achieve a desired coupling coefficient during the first operating mode and a second RF coupler designed to achieve a desired coupling coefficient during the second operating mode. However, including separate RF couplers may result in an increase in the footprint and / or package size of the FEM100. In addition, the switching circuits required for switching between these RF couplers may also increase the footprint and / or package size of the FEM100 and introduce additional losses into the signal path.

[0061] Therefore, an improved bidirectional coupler is provided. In at least one embodiment, the bidirectional coupler includes a switchable inductor configured to give an adjustable coupling coefficient. In some examples, the bidirectional coupler is configured to support a range of signal frequencies. In a given example, the coupling coefficient is adjusted to minimize insertion loss over the range of signal frequencies while maintaining a substantially constant coupling power level.

[0062] Figure 3 is a schematic diagram of a bidirectional coupler 300 relating to several aspects described herein. As shown, the coupler 300 includes a main transmission line 302, a coupling transmission line 304, and a switch 306. In one example, the coupling transmission line 304i includes a first segment 304a and a second segment 304b. In some examples, the first segment 304a and the second segment 304b are transmission lines corresponding to switchable inductors. The switch 306 operates to selectively couple the first segment 304a to the second segment 304b in order to change the length (i.e., inductance) of the coupling transmission line 304.

[0063] In one example, the main transmission line 302 includes a first port (CPL_IN) and a second port (CPL_ANT), and the coupled transmission line 304 includes a first forward port (CPL_FL), a second forward port (CPL_FH), and a reverse port (CPL_R). In some examples, the first port (CPL_IN) of the main transmission line 302 is configured to be coupled to the output of a filter or amplifier of the FEM (e.g., the filtering subsystem 120 or power amplifier module 110 of FEM 100). Similarly, the second port (CPL_ANT) of the main transmission line 302 may be configured to be coupled to the input of a switch / antenna port of the FEM (e.g., a port connected to the switching circuit 150 or antenna 140 of FEM 100).

[0064] In some examples, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, the signal is output via the second port (CPL_ANT) of the main transmission line 302, and a coupling signal is provided to the first or second forward port (CPL_FL, CPL_FH) of the coupling transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the signal is output via the first port (CPL_IN) of the main transmission line 302, and a coupling signal is provided to the reverse port (CPL_R) of the coupling transmission line 304.

[0065] As described above, the switch 306 can operate to selectively couple the first segment 304a and the second segment 304b of the coupled transmission line 304 in order to change the length (i.e., inductance) of the coupled transmission line 304. In one example, the switch 306 is configured to selectively couple the first forward port (CPL_FL) of the first segment 304a to the switch port (CPL_SWT) of the second segment 304b in order to couple the first segment 304a and the second segment 304b of the coupled transmission line 304. Therefore, the coupler 300 is configured to operate in different operating modes corresponding to the state of the switch 306. For example, in the first operating mode, the switch 306 is on (i.e., closed) and the first segment 304a of the coupled transmission line 304 is coupled to the second segment 304b of the coupled transmission line 304. Similarly, in the second operating mode, switch 306 is turned off (i.e., open), and the first segment 304a of the coupled transmission line 304 is uncoupled from the second segment 304b of the coupled transmission line 304.

[0066] Figures 4A and 4B are schematic diagrams of the bidirectional coupler 300 operating in a first and second operating mode relating to several aspects described herein. As shown in Figure 4A, in the first operating mode, switch 306 is turned on (i.e., closed) to couple the first segment 304a and the second segment 304b of the coupling transmission line 304. In one example, the first segment 304a and the second segment 304b are coupled together, the coupling transmission line 304 has a first length L1, and the coupler 300 has a first coupling coefficient CF1 corresponding to the first length L1. In some examples, the first length L1 of the coupling transmission line 304 corresponds to the coupling length of the first segment 304a and the second segment 304b of the coupling transmission line 304. Therefore, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, a coupling signal is supplied to the second forward port (CPL_FH) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, a coupling signal is supplied to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304.

[0067] Similarly, as shown in Figure 4B, in the second operating mode, switch 306 is turned off (i.e., open) to decouple the first segment 304a and the second segment 304b of the coupled transmission line 304. In one example, when the first segment 304a and the second segment 304b are decoupled, the coupled transmission line 304 has a second length L2, and the coupler 300 has a second coupling coefficient CF2 corresponding to the second length L2. In some examples, the second length L2 of the coupled transmission line 304 corresponds to the length of the first segment 304a of the coupled transmission line 304. Therefore, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, a coupling signal is applied to the first forward port (CPL_FL) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, a coupling signal is applied to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304.

[0068] As described above, the length of the coupled transmission line 304 in the first operating mode (i.e., L1) is longer than the length of the coupled transmission line 304 in the second operating mode (i.e., L2). Therefore, the coupling coefficient of the coupler 300 in the first operating mode (i.e., CF1) is greater than the coupling coefficient of the coupler 300 in the second operating mode (i.e., CF2). As the coupling coefficient increases with frequency, the coupler 300 switches between the first and second operating modes to minimize insertion loss, based on the frequency of the signal applied to the main transmission line 302. For example, for a lower frequency signal, the coupler 300 may operate in the first operating mode (i.e., with a large coupling coefficient CF1). Similarly, for an upper frequency signal, the coupler 300 may operate in the second operating mode (i.e., with a small coupling coefficient CF2).

[0069] Figure 5 shows several graphs of simulated performance results for the bidirectional coupler relating to the various aspects described herein. For example, graph 510 includes the coupling coefficients of the bidirectional coupler 300 over frequency, and graph 520 shows the insertion loss of the bidirectional coupler 300 over frequency.

[0070] In one example, the first trace 512 of Graph 510 represents the coupling coefficient of the coupler 300 while it is operating in the first operating mode (i.e., CF1). Similarly, the second trace 514 of Graph 510 represents the coupling coefficient of the coupler 300 while it is operating in the second operating mode (i.e., CF2). As shown in the figure, due to the length of the coupled transmission line 304, the first coupling coefficient CF1 remains greater than the second coupling coefficient CF2 over the entire frequency sweep from 0.5 GHz to 4 GHz. As described above, the coupler 300 can operate in the first and second operating modes based on frequency. In one example, the coupler 300 operates in the first operating mode for the first frequency range 516 (approximately 0.5 GHz to 1.5 GHz) and in the second operating mode for the second frequency range 518 (approximately 1.5 GHz to 2.75 GHz). By switching between a first operating mode and a second operating mode based on frequency, the coupler 300 can provide a substantially constant coupling coefficient over frequency ranges 516 and 518. For example, the coupler 300 can provide a coupling coefficient of approximately -27.1 dB at approximately 0.6 GHz (i.e., the first frequency range 516) while operating in the first operating mode, and a coupling coefficient of approximately -25.1 dB at approximately 1.7 GHz (i.e., the second frequency range 518) while operating in the second operating mode. In a given example, the coupler 300 can provide a coupling coefficient that varies by less than ±3 dB over the entire operating frequency range (e.g., 0.5 GHz to 3 GHz). In some examples, a substantially constant coupling coefficient allows the coupler 300 to provide a coupling power at a substantially constant power level over frequency at the forward and reverse ports (CPL_FL, CPL_FH, CPL_R) of the coupled transmission line 304.

[0071] In one example, the first trace 522 of Graph 520 represents the insertion loss of the coupler 300 while operating in the first operating mode (i.e., CF1), and the second trace 524 represents the insertion loss of the coupler 300 while operating in the second operating mode (i.e., CF2). In some examples, the insertion loss of the coupler 300 can be minimized by maintaining a substantially constant coupling coefficient over frequency. For example, the coupler 300 may have an insertion loss of approximately -0.10 dB at approximately 1.5 GHz (i.e., frequencies within the first frequency range 516) while operating in the first operating mode, and an insertion loss of approximately -0.12 dB at approximately 2.7 GHz (i.e., different frequencies within the second frequency range 518) while operating in the second operating mode. In a given example, the insertion loss of the coupler 300 is less than -0.15 dB over the entire operating frequency range (e.g., 0.5 GHz to 3 GHz). In some cases, by minimizing insertion loss over frequency, radio frequency signals can be applied to the first and second ports (CPL_IN, CPL_ANT) of the main transmission line 302 at a substantially constant power level over frequency. In addition, reflection losses in the main transmission line 302 can be kept substantially constant even when switching between the first and second operating modes.

[0072] As described above, the coupling coefficient of the coupler 300 can be adjusted to minimize insertion loss over frequency while maintaining a substantially constant power level of the coupled signal supplied to the forward and reverse output ports (CPL_FL, CPL_FH, and CPL_R). Therefore, the coupler 300 can be integrated into the device (e.g., FEM100) without the use of extra components (e.g., attenuators) to adjust the power level of the coupled signal. Similarly, the RF source supplying the input signal to the coupler 300 (e.g., power amplifier module 110) can be operated at a constant output power level over frequency, thereby improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM100. In addition, the compact footprint of the coupler 300 can reduce the footprint or package size of the FEM100.

[0073] In some examples, the bidirectional coupler 300 can be arranged with additional components (e.g., adjustable termination components) that support multimode operation. Similarly, the coupler 300 can be arranged with additional components that support integration into existing FEM architectures and layouts. Figure 6 shows a bidirectional coupler 600 relating to several aspects described herein. In one example, the coupler array 600 includes a bidirectional coupler 300, an adjustable termination circuit 602, and several switches S1 to S6.

[0074] As described above, the coupler 300 includes a main transmission line 302 having a first port (CPL_IN) and a second port (CPL_ANT), a coupled transmission line 304 having a first forward port (CPL_FL), a second forward port (CPL_FH), and a reverse port (CPL_R), and a switch 306 configured to selectively couple the first segment 304a and the second segment 304b of the coupled transmission line 304.

[0075] In one example, the first switch S1 is configured to selectively couple the reverse port (CPL_R) of the coupled transmission line 304 to the adjustable termination circuit 602, the second switch S2 is configured to selectively couple the first forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602, and the third switch S3 is configured to selectively couple the second forward port (CPL_FH) of the coupled transmission line 304 to the adjustable termination circuit 602. Similarly, the fourth switch S4 is configured to selectively couple the reverse port (CPL_R) of the coupled transmission line 304 to the common output section (CPL_OUT), the fifth switch S5 is configured to selectively couple the first forward port (CPL_FL) of the coupled transmission line 304 to the common output section (CPL_OUT), and the sixth switch S6 is configured to selectively couple the second forward port (CPL_FH) of the coupled transmission line 304 to the common output section (CPL_OUT).

[0076] In some examples, the adjustable termination circuit 602 is selectively coupled to multiple ports of the coupler 300 to control the directivity of the coupler. For example, the adjustable termination circuit 602 may be coupled to a port corresponding to an isolation port in each operating mode of the coupler 300. In one example, when the coupler 300 is providing forward coupling, the adjustable termination circuit 602 may be coupled to the reverse port (CPL_R) of the coupled transmission line 304. Similarly, when the coupler 300 is providing reverse coupling, the adjustable termination circuit 602 may be coupled to one of the forward ports (CPL_FL, CPL_FH) of the coupled transmission line 304. In one example, the adjustable termination circuit 602 includes at least one adjustable / tunable RLC (resistor-inductive-capacitor) circuit. This adjustable / tunable RLC includes one or more tunable resistive, inductive, or capacitive elements, or a combination thereof. In some examples, the adjustable termination circuit 602 is adjusted / tuned based on the operating mode of the coupler 300. For example, during the first operating mode, the adjustable termination circuit 602 may be adjusted to provide a first termination impedance optimized for lower frequency signals (e.g., a first frequency range 516). Similarly, during the second operating mode, the adjustable termination circuit 602 may be adjusted to provide a second termination impedance optimized for upper frequency signals (e.g., a second frequency range 518). In a given example, the adjustable termination circuit 602 may be adjusted to provide a termination impedance for a specific signal frequency.

[0077] In some examples, the coupling coefficient of the coupler 300 can be adjusted to address losses associated with switches S1 to S6. For example, the width and / or length of the first segment 304a and the second segment 304b of the coupled transmission line 304 can be adjusted to increase or decrease the coupling coefficient of the coupler 300. In a given example, the spacing between the main transmission line 302 and the coupled transmission line 304 can be adjusted to increase or decrease the coupling coefficient of the coupler 300.

[0078] Figures 7A to 7D are schematic diagrams of the bidirectional coupler array 600 operating in various states relating to the multiple aspects described herein.

[0079] Figure 7A shows the first state of the bidirectional coupler array 600. In one example, the first state corresponds to a weak coupling in the forward direction. In some examples, the bidirectional coupler array 600 may operate in the first state to provide forward coupling to an upper frequency signal (e.g., a second frequency range 518). As shown in the figure, when the coupler 300 operates in the second operating mode, switch 306 is turned off (i.e., open), and the first segment 304a and the second segment 304b of the coupled transmission line 304 are decoupled. Therefore, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, the coupled signal is supplied to the first forward port (CPL_FL) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304. In one example, a fifth switch S5 is turned on (i.e., closed), and the coupled signal from the first forward port (CPL_FL) is directed to the common output port (CPL_OUT). In addition, the first switch S1 is turned on (i.e., closed) and the reverse port (CPL_R) of the coupled transmission line 304 is coupled to the adjustable termination circuit 602. When the coupler 300i is operating in the second operating mode, the adjustable termination circuit 602 may be configured to provide a second termination impedance optimized for upper-frequency signals during the first state of the coupler array 600.

[0080] Figure 7B shows the second state of the bidirectional coupler array 600. In one example, the second state corresponds to strong coupling in the forward direction. In some examples, the bidirectional coupler array 600 may operate in the second state to provide forward coupling to lower frequency signals (e.g., the first frequency range 516). As shown in the figure, when the coupler 300 operates in the first operating mode, switch 306 is turned on (i.e., closed) and the first segment 304a and the second segment 304b of the coupled transmission line 304 are coupled. Therefore, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, the coupled signal is applied to the second forward port (CPL_FH) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304. In one example, the sixth switch S6 is turned on (i.e., closed) to direct the coupling signal from the second forward port (CPL_FH) to the common output port (CPL_OUT). In addition, the first switch S1 is turned on (i.e., closed) to couple the reverse port (CPL_R) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300 is operating in the first operating mode, the adjustable termination circuit 602 may be configured to provide a first termination impedance optimized for lower frequency signals during the second state of the coupler array 600.

[0081] Figure 7C shows the third state of the bidirectional coupler array 600. In one example, the third state corresponds to a weak coupling in the reverse direction. In some examples, the bidirectional coupler array 600 may operate in the third state to provide reverse coupling to an upper frequency signal (e.g., a second frequency range 518). As shown in the figure, when the coupler 300 operates in the second operating mode, switch 306 is turned off (i.e., open), and the first segment 304a and the second segment 304b of the coupled transmission line 304 are decoupled. Therefore, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the coupled signal is applied to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304. In one example, the fourth switch S4 is turned on (i.e., closed), and the coupled signal from the reverse port (CPL_R) is directed to the common output port (CPL_OUT). In addition, the second switch S2 is turned on (i.e., closed) to couple the first forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300i is operating in the second operating mode, the adjustable termination circuit 602 may be configured to provide a second termination impedance optimized for upper-frequency signals during the third state of the coupler array 600.

[0082] Figure 7D shows the fourth state of the bidirectional coupler array 600. In one example, the fourth state corresponds to a strong coupling in the reverse direction. In some examples, the bidirectional coupler array 600 may operate in the fourth state to provide reverse coupling to a lower frequency signal (e.g., a first frequency range 516). As shown in the figure, when the coupler 300 operates in the first operating mode, switch 306 is turned on (i.e., closed) and the first segment 304a and the second segment 304b of the coupled transmission line 304 are coupled. Therefore, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the coupled signal is applied to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304. In one example, the fourth switch S4 is turned on (i.e., closed) and the coupled signal from the reverse port (CPL_R) is directed to the common output port (CPL_OUT). In addition, the third switch S3 is turned on (i.e., closed) to couple the second forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300 is operating in the first operating mode, the adjustable termination circuit 602 may be configured to provide a first termination impedance optimized for lower frequency signals during the fourth state of the coupler array 600.

[0083] Although the bidirectional coupler 300 has been described above as having two selectable segments (i.e., a first segment 304a and a second segment 304b), it should also be understood that the bidirectional coupler 300 may be configured to have a coupling transmission line having a different number of segments. For example, the coupler 300 may be configured so that the coupling transmission line has three segments to provide optimized coupling performance for three different signal frequencies (or bandwidths / ranges). Thus, the third segment can be coupled to the first segment 304a and / or the second segment 304b of the coupling transmission line 304 during a third operating mode to provide a third coupling coefficient. In some examples, additional switches may be included to selectively couple multiple segments of the coupling transmission line.

[0084] Similarly, although the bidirectional coupler 300 has been described above as having a primary transmission line 302 and a coupled transmission line 304, it should be understood that the bidirectional coupler 300 may also be configured to include a separate inductor (i.e., one having a coil or winding). For example, the bidirectional coupler 300 may be configured to include a primary inductor corresponding to the primary transmission line 302 and a coupling inductor corresponding to the coupled transmission line 304. In some examples, the coupling inductor may include two or more inductors corresponding to the first segment 304a and the second segment 304b of the coupled transmission line 304. In some examples, the primary inductor may be referred to as the primary winding of the bidirectional coupler 300, and the coupling inductor may be referred to as the secondary winding of the bidirectional coupler 300.

[0085] Furthermore, it should be understood that the bidirectional coupler 300 and the bidirectional coupler array 600 may be used in a variety of wireless applications. For example, the coupler 300 and the coupler array 600 may be configured for use in wireless local area network (WLAN) applications, ultra-wideband (UWB) applications, wireless personal area network (WPAN) applications, 4G cellular applications, and LTE cellular applications.

[0086] In some examples, the switches 306 of the coupler 300 and / or the switches S1-S6 of the coupler array 600 may include gallium nitride (GaN), gallium arsenide (GaAs), or silicon germanium (SiGe) transistors. In some examples, the transistors may be configured as heterojunction bipolar transistors (HBTs), high electron mobility transistors (HEMTs), metal oxide semiconductor field-effect transistors (MOSFETs), and / or complementary metal oxide semiconductors (CMOS). In some examples, the coupler 300 or the coupler array 600, or one or more components of the coupler 300 or the coupler array 600, may be fabricated using silicon-on-insulator (SOI) techniques.

[0087] As described above, the coupler 300 can be arranged in a compact layout. For example, Figure 8 is a schematic diagram of the layout 800 of the coupled transmission line 304 of the coupler 300 relating to the multiple aspects described herein. As shown in the figure, the first segment 304a and the second segment 304b of the coupled transmission line 304 can be arranged in a compact layout. In one example, the footprint of the coupler 300 can be reduced by 50% compared to an alternative multi-frequency coupling solution (e.g., two different couplers).

[0088] The embodiments of the bidirectional coupler 300 and / or bidirectional coupler array 600 described herein can be advantageously used in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronic products, components of consumer electronic products, electronic test equipment, and cellular communication infrastructure such as base stations. Examples of electronic devices may include, but are not limited to, routers, gateways, mobile phones such as smartphones, cellular front-end modules, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, e-readers, wearable computers such as smartwatches, personal digital assistants (PDAs), electrical appliances such as microwave ovens and refrigerators, automobiles, stereo systems, digital music players such as DVD players, CD players, and MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, healthcare monitoring devices, vehicle electronic systems such as automotive electronic systems or avionics systems, peripheral devices, wristwatches, and clocks. Furthermore, electronic devices may also include unfinished products.

[0089] As described above, an improved bidirectional coupler is provided. In at least one embodiment, the bidirectional coupler includes a switchable inductor configured to give an adjustable coupling coefficient. In some examples, the bidirectional coupler is configured to support a range of signal frequencies. In a given example, the coupling coefficient is adjusted to minimize insertion loss over the range of signal frequencies while maintaining a substantially constant coupling power level.

[0090] While several aspects of at least one embodiment have been described above, it should be understood that those skilled in the art will readily recall various modifications, alterations, and improvements. Such modifications, alterations, and improvements are intended to be part of this disclosure and to be within the scope of the invention. Therefore, the above description and drawings are merely illustrative, and the scope of the invention should be determined by the appropriate configuration of the appended claims and their equivalents.

Claims

1. 1. A radio frequency signal coupler comprising: An input port; An output port; a main transmission line coupled between the input port and the output port; a coupled transmission line electromagnetically coupled to the main transmission line; Including, The coupled transmission line includes: A first transmission line; A second transmission line; a switch configured to couple the first transmission line and the second transmission line during a first mode of operation and to decouple the first transmission line and the second transmission line during a second mode of operation; a radio frequency signal coupler including:

2. 2. The radio frequency signal coupler of claim 1 , wherein the switch is configured to couple the first transmission line and the second transmission line to provide a first coupling coefficient during the first mode of operation and to decouple the first transmission line and the second transmission line to provide a second coupling coefficient during the second mode of operation.

3. the first mode of operation corresponds to configuring the radio frequency signal coupler to operate within a first frequency range; the second mode of operation corresponds to configuring the radio frequency signal coupler to operate within a second frequency range; 3. The radio frequency signal coupler of claim 2, wherein said second frequency range and said first frequency range are different.

4. 4. The radio frequency signal coupler of claim 3, wherein the first coupling factor across the first frequency range is within ±3 dB of the second coupling factor across the second frequency range.

5. 4. The radio frequency signal coupler of claim 3, wherein the radio frequency signal coupler operates to maintain a substantially constant insertion loss between the input port and the output port across the first frequency range and the second frequency range in the first and second operating modes.

6. 4. The radio frequency signal coupler of claim 3, wherein the radio frequency signal coupler is configured as a bidirectional coupler, the input port and the output port being each configured to receive an input radio frequency signal and provide an output radio frequency signal.

7. further comprising at least one forward output port and one reverse output port; 7. The radio frequency signal coupler of claim 6, wherein the coupled transmission line is coupled between the at least one forward output port and the one reverse output port.

8. 8. The radio frequency signal combiner of claim 7, wherein the at least one forward output port is configured to provide a forward coupled signal when the input radio frequency signal is received at the input port.

9. 9. The radio frequency signal coupler of claim 8, wherein the radio frequency signal coupler operates to maintain a substantially constant power level of the forward coupled signal across the first and second frequency ranges in the first and second operating modes.

10. 8. The radio frequency signal combiner of claim 7, wherein the reverse output port is configured to provide a reverse coupled signal when the input radio frequency signal is received at the output port.

11. 11. The radio frequency signal coupler of claim 10, wherein the radio frequency signal coupler operates to maintain a substantially constant power level of the reverse coupled signal across the first and second frequency ranges in the first and second operating modes.

12. 8. The radio frequency signal combiner of claim 7, wherein said at least one forward output port and said one reverse port are selectively coupled to a common output port.

13. 8. The radio frequency signal combiner of claim 7, wherein the at least one forward output port and the one reverse output port are selectively coupled to an adjustable termination circuit.

14. 14. The radio frequency signal coupler of claim 13, wherein the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

15. the coupled transmission line includes a third transmission line; the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during a third mode of operation corresponding to a third frequency range; 4. The radio frequency signal coupler of claim 3, wherein said third frequency range is different from said first frequency range and said second frequency range.

16. 16. The radio frequency signal coupler of claim 15, wherein the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during the third mode of operation to provide a third coupling coefficient.

17. 1. A method of operating a radio frequency signal combiner, comprising: receiving a radio frequency signal at one of the input port and the output port; providing said radio frequency signal to a main transmission line coupled between said input port and said output port; electromagnetically coupling a portion of the radio frequency signal to a coupled transmission line including a first transmission line and a second transmission line; operating a switch to couple the first transmission line and the second transmission line during a first mode of operation and to decouple the first transmission line and the second transmission line during a second mode of operation; A method comprising:

18. 20. The method of claim 17, wherein operating the switch to couple the first transmission line and the second transmission line during the first mode of operation further comprises providing a first coupling coefficient to the radio frequency signal coupler.

19. The method of claim 18 , wherein the first coupling coefficient corresponds to a first frequency range.

20. 20. The method of claim 19, wherein operating the switch to decouple the first transmission line and the second transmission line during the second mode of operation further comprises providing a second coupling coefficient to the radio frequency signal coupler.

21. the second coupling coefficient corresponds to a second frequency range; 21. The method of claim 20, wherein the second frequency range and the first frequency range are different.

22. 22. The method of claim 21, wherein the first coupling factor over the first frequency range is within ±3 dB of the second coupling factor over the second frequency range.

23. 22. The method of claim 21, further comprising: operating the radio frequency signal coupler to maintain a substantially constant insertion loss between the input port and the output port across the first frequency range and the second frequency range in the first and second operating modes.

24. 1. A radio frequency signal coupler comprising: An input port; An output port; a main inductance coupled between the input port and the output port; a coupling inductance that is electromagnetically coupled to the main inductance; Including, The coupling inductance is A first inductance; A second inductance; a switch configured to couple the first inductance and the second inductance during a first mode of operation and to decouple the first inductance and the second inductance during a second mode of operation; a radio frequency signal coupler including:

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